1. Field of the Invention
The present invention relates to a power supply control device including circuitry for holding the power supply from a battery to a battery-operated circuit for a certain time period after a power switch is turned off.
2. Description of the Prior Art
Conventionally, a camera exposure meter circuit, automatic exposure control circuit or the like is provided with circuitry for supplying power switch on in response to the shutter buttom operation at its half-depression position, which is shallower than the stroke where the shutter release takes place and for maintaining or holding the power supply operative to supply power for a certain time period even if an operator releases his finger from the shutter button to facilitate camera handling.
In a camera with such circuitry, an operator can view the exposing condition or exposure control status for a certain time period after releasing his finger from the shutter button. In such conventional power supply holding circuits, however, the power supply holding time is set as a constant value even where a battery is weak or depleted. This kind of circuit with a power supply holding function, which is directed only to the purpose of facilitating camera handling, and is not necessarily required to take a photograph, has a disadvantage in that consumption of a batter is hastened.